The operating frequencies of up to 100 MHz occurring in current distribution systems require careful configuration of all components of the distribution system, especially also of the connectors in the patch fields. Three main demands are made on the transmission performance of the components, namely with respect to the insertion loss, terminal return loss and the cross-talk performance. Apart from cable attenuation, the cross-talk performance in particular is the factor which determines maximum transmission performance. For this reason, additional compensation measures, apart from an originally cross-talk-deficient design, are normally necessary in individual components. The requirements to be fulfilled by the components of commercial distribution systems are set out in the US standard ANSI/EIA/TIA-568 ("Commercial Building Telecommunications Wiring Standard") and the associated "Supplement Technical Systems Bulletin" (TIA/EIA TSB 40). Of special interest is category 5 of this standard, which requires of connectors a cross-talk attenuation (NEXT) of at least -40 dB between the individual board pairs at an operating frequency of 100 MHz. This requirement can barely be fulfilled any longer by standard connectors having even contact clearance and necessitates complicated board geometries or balancing circuits.
The specification of U.S. Pat. No. 5,295,869 discloses a connector in which a capacitive balancing of cross-talk occurs on an additional plate by means of closely adjoining through-hole platings. This same document also itemizes the other known possibilities for balancing the cross-talk, namely: use of discrete balancing capacitors, design of capacitive surfaces on associated printed circuit boards, inductive coupling by means of parallel conductivity on associated printed circuit boards, as well as additional balancing conductor sections.
The drawbacks to these known balancing processes for connectors are deficient compatibility of discrete balancing capacitors or additional balancing conductor sections, as well as increased manufacturing costs because of additionally required processes.
The specification of DE 43 25 952.9 discloses a contact board for distribution systems which enables cross-talk attenuation of better than -60 dB in a configuration as circuit board or terminal board by contraction of the contact clearance between both conductors of the twisted pairs with constant contact clearance between the different double wires. The disadvantage is that with this particular configuration of the contact board as disconnecting board, the cross-talk attenuation between opposite double wires rises to -40 dB during use of conventional connectors, accordingly requiring further balancing measures on the connector.